How to tell there is a serial request

[Darrel Taylor]

Yes, HSERIN gets it's data from the USART's buffer.

In the main loop you could ...

    IF HaveTime AND RCIF THEN GOSUB Serial

The PC will wait until the PIC sends it.
Don't see a reason to tell it there's no time to talk now. But maybe your app needs that.

[cncmachineguy]

Thanks again Darrel for the explaination.

The reason to send back a busy byte is for the user. Being me if I try to talk to the card and get nothing, I will likely forget its because my drives are enabled and assume there is something wrong. Then go and spend as much time as possible just to find out all is working as it should.